Machine for grinding facets in lens edges



June 16, 1942. A. ANDER$QN 1 .7

MACHINE FOR GRINDINQF'ACETS IN LENS EDGBS Filed Feb. 29, 1940 3 Sheets-Sheet 1 I ll.

' June 16, 1942.

A. 1.. ANDERSON 2, ,886

MACHINE FOR GRINDING FACETS IN LENS EDGES Filed Feb. 29, 1940 5 Sheets-Sheet 2 7 Inveniar v AZZorrzqys June 16, 1942. A, ANDERSON 2,286,886

MACHINE FOR GRINDING FACE'II'S IN LENS EDGES 3' Sheets-Sheet 5 Filed Feb. 29, 1946 Aiiomeys Patented June 16, 1942 grass lt/IACHINE FOR GRINDING FACETS IN LENS EDGES Application February 29, 1940, Serial No. 321,441

3 Claims.

This invention relates to a method and apparatus for grinding facets and similar cuts on the edges of lenses and particularly optical lenses.

In the prior Patent No. 2,174,304., issued jointly to Albert J. Anderson and James G Wescott September 26, 1939, there is disclosed an optical lens having facets in its edges, the object being to diffuse light at the edge of the lens so that said lens will blend in with the face of the wearer and become considerably less conspicuous. The provision of facets at the lens edge eliminates the usual prominent and well defined appearance of the ordinary lens due to the reflection and refraction of light at said edge.

It is, of course, possible to grind facets in lens edges'by hand, but it is extremely difficult to produce facets of uniform size and shape without some definite guiding and holding means.

One of the objects of my invention is to provide apparatus for holding a lens in proper position with relation to a grinding tool so that the lens will be held rigidly during the grinding operation.

Another object of the invention is to provide grinding apparatus wherein the lens can be progressively moved from one position to another to secure the desired spacing of facets around the edge.

Another object of the invention is to provide apparatus of this type in combination with a grinding tool having differently shaped grinding surfaces to produce different types of cuts on the edge of the lens.

A further object of the invention is to provide lens clamping means wherein the lens is not only rigidly held but wherein it can be quickly and easily clamped and released.

Another object of the invention is to provide means for grinding facets of equal size and distribution On lenses of irregular shape at their edges.

Still another object is to provide an improved method of grinding facets on lens edges.

These and other objects and advantages of the invention will more fully appear from the following description made in connection with the accompanying drawings, wherein like reference characters refer to the same parts throughout the views, and, in which:

Fig. 1 is a plan view of the apparatus;

Fig. 2 is a side elevation of the apparatus in the position shown in Fig. 1;

Fig. 3 is a section taken approximately on the line 33 of Fig. 1;

Fig. 4 is a section taken approximately on the line 4-4 of Fig. 3;

Fig. 5 is a fragmentary view partially in section of the lens holding base and slide;

Fig. 6 is a section taken approximately on the line 6-6 of Fig. 3;

Fig. 7 is an enlarged detail of the depth cutting gauge associated with the grinding wheel;

Fig. 8 is an enlarged fragmentary detail of a portion of the telescoping lens clamp structure;

Fig. 9 is a plan view of a modified form of structure;

Fig. 10 is a side elevation thereof;

Fig. 11 is a plan view of another form of construction;

Fig. 12 is a side elevation of the form shown in Fig. 11;

Fig. 13 is a plan view of one of the cut spacing wheels with a lens superimposed thereon to show the relation between the spacing of the teeth on the wheel and the spacing of facets on the edge of an irregularly shaped lens; and

Fig. 14 is a fragmentary View of a type of lens edge formed in accordance with'my invention.

In the embodiment shown in Figs. 1 through 8 there is illustrated a bed or base l4 which is adapted to rest upon a table or work bench. A motor 15 is mounted on the base and this motor is geared by a belt Hi to a pulley ll on a shaft I8, the latter being suitably journalled in a standard I9 which extends upwardly from the base I4. The shaft l8 carries a rotary grinding wheel 29. Also supported bythe standard [9 is a water receptacle 2| with an outlet 22 which is adapted to drip water on a sponge or similar absorbent article 23 which is mounted in a drip pan 24 also supported by the standard l9. Mounted adjacent the grinding wheel is a relatively flat bar 25 pivotally connected to the base 14 by a bolt 26 and wing nut 21. The bolt 26 is preferably in alignment with a plane through the grinding wheel 20 normal to the axis of said wheel. The bar 25 at its right-hand or outer end. rests upon a raised slide surface 28- and the bar 25 is adapted tojswing from the position shown in Fig. 1. where it rests against a stop 29 to the opposite side of the arcuate slide 29 and against a stop 30. In each of these-two positions the bar 25 may be locked by a small thumb screw 3| which is adapted to fit in a small detent asthe one shownat 32 adjacent the stop 39. The bar 25 is shown elevated above the base It intermediate the ends of the bar to permit sliding movement of a vise carrier 33 toward and away from the grinding wheel 20. The body 34 of the vise or lens holder unit is pivotally mounted on a cross shaft 35 which in turn is supported by the vise carrier 33. The main axial portion of the lens holder body 34 which extends from the shaft 35 carries a post 36 which extends upwardly a considerable distance and at its upper end is provided with a lens contacting pad 31 of some relatively soft material such as rubber. Extending laterally and thence upwardly from the lens holder body 34 is an arm 38 which at its upper end terminates in an open ended cylinder 38a. On the upper end of the lens holder unit is a movable arm 39 which at its right-hand end has a downwardly extending cylindrical portion 39a which is slidable in the cylindrical upper end 38a of the arm 39. The cylinder 36a, as best shown in Fig. 8, is provided with a slot 40 in which is adapted to reciprocate a pin 4|, said pin being anchored in the cylinder 39a on the movable arm 39. A bolt 42 extends downwardly through the concentric cylinders 33a and 39a and at its lower end is secured in the lens holder body arm 33. A coil spring 43 is positioned on the bolt 42 and confined between the bottom of the cylinder 39a and a pair of locked nuts 44 on said bolt 42. The spring 43 is under compression and urges the movable arm 39 downwardly toward the lens holder body 34 and its upwardly extending post 36. The left-hand end of the movable arm 39 is provided with a rubber or other yielding pad 45 similar to the pad 31 on the top of the post 36. A lens 46 is shown clamped between the pads or grips 31 and 45 to hold the lensin position for grinding. In order to facilitate releasing of the lens I provide a collar 41 on the cylinder 39a and a lever 48 on the cylinder 36a whereby the lever can be pressed inwardly to force cylinder 39aand movable arm 39 upwardly to open the lens clamp provided by the post 36, the arm 39 and the pads 31 and 45.

The vise or lens holding body 34 is slidable with the vise carrier 33 towards and away from the grinding wheel 2|] and the body 34 is also tiltable on its pivot 35. A set screw 33a is provided to lock the vise carrier 33 to the swingable arm 25 so that the carrier 33 can be locked to maintain its position relative to the grinding wheel during the grinding operation. When the vise or lens holder body 34 is tilted to a vertical position away from the grinding wheel it will rest in this upright position due to the overbalancing weight of the offset arm 38 and leaf spring 34a,

and a flat stop 34b is provided as a base for said lens holder to rest upon in said vertical position.

The post 36 is rotatable with respect to its supporting body 34 and the upper lens contacting pad 45 is rotatable in its supporting arm 39. Thi rotary motion permits turning of the lens 46 to bring successive edge portions into proper position for grinding contact with the rotary grinding tool 20. Mounted for rotation with the post 36 is a pair of toothed spacing wheels 49 and 50. Extending inwardly toward said wheels from the upwardly extending portion of the body arm 36 is a slidable pin which is normally urged toward the Wheels 49 by a compression spring 52. The left-hand or inner end of the pin 5| is provided with a half-tooth 53 Which extends inwardly further than another half-tooth portion 54. The pin 5| is adapted to be rotated 180 degrees to bring the elongated pin tooth portion 53 into contact with either the toothed wheel 49 or 56. In order to maintain the pin 5| in either of its two positions the outer end of the pin is provided with a pair of longitudinal grooves aaeaese .7

55 which are adapted to selectively receive a small spring catch pin 56.

The toothed wheels 49 and 56 are provided to permit the use of wheels having teeth with two different types of spacing and it is necessary only to rotate the pin 5| from one position to its other position as just described to permit step-by-step rotation of the lens clamp and lens for different degrees of steps depending upon the spacing desired between the facets on the lens edge and the size of the facets to be produced. In some types of lenses it might be desirable to space the facets farther apart than in others. In such case the toothed wheels 49 and 50 may each have irregularly spaced teeth which are set at different distances on the two wheels. However, in Fig. 13 I have diagrammatically illustrated a toothed wheel 51 whereon it will be noted that the teeth on the edge of the wheel are not regularly spaced around its circumference. Such a toothed Wheel is provided to produce regularly spaced facets on an irregularly shaped lens such as the lens 58. The radial lines projected from the center of the lens are shown to be different distances apart in several portions of the lens edge and in the edge of the toothed wheel 51. Where the edge of the lens is closer at certain points to its center the corresponding wheel teeth are placed farther apart, and where the lens edge is farther from the center the teeth on the wheel 51 are placed a little closer together to compensate for the different lengths of radii from the lens center to its edge. It is not necessary and imperative that an irregularly toothed wheel such as the wheel 51 be used with an irregularly shaped lens, but it can be utilized if even spacing of facets is desired.

The grinding wheel 26 is substantially of disc shape and it will be seen that the two circumferential corners of the wheel are of different shapes. As viewed, in Fig. 1, there is provided a sharp corner 59 and a rounded corner 60. This obviously will produce different types of cuts on the lens when the lens holder is shifted from the position shown in Fig. 1 to a position against the stop 36 at the opposite end of the arcuate slide track 26. The circumference of the wheel 20 is also provided with a groove 6| for rounding off and polishing the edges of lenses where desired.

Mounted on one side of the grinding wheel supporting standard I9 is a bracket 62 which is adjustably mounted for rotation about the grinding wheel journal 63, a set screw 64 being provided to clamp the bracket 62 in a desired position. The outer end of the bracket 62 carries an arcuate pin 65 which is adapted to slidably support a cutting gauge 66. This gauge, as shown best in Fig. 1, extends around the rounded corner of the wheel 26 and across its relatively fiat circumferential rim. The gauge 66', as shown in Fig, 7, is substantially V-shaped in cross section and at the bottom of the V there is provided a slot 61 with adjacent portions of the gauge 66 defining the slot being tapered inwardly toward the slot 61. This gauge 66 with its slot 61 permits the edge of the lens to extend slightly therethrough to contact a corner of the grinding wheel, and the gauge 66 limits the extent to which the lens 46 can b projected toward the wheel 26. The sliding movement of the gauge 66 relative to its supporting pin- 65 isprovided to permit exact registration of the corner of the lens edge with the slot 61 in said gauge.

When grinding a lens in accordance with the teachings of my invention it is preferred that facets be formed on both corners of the edge and in order to do so it is, of course, necessary to grind the edge at one side and then reverse the lens in the holder and grind the other side. In addition afurther grinding operation can be performed across the edge to provide grooves parallel to the axis of the lens in order to further diffuse light at the lens edges. The grinding of transverse grooves is preferably done with the sharp corner 59 on the grind stone 2!] with the lens holder 34 in the positions shown in Figs. 1 and 2, i. e., with the swinging bar 25 against the slide stop 29. The holder 34 is th n placed in the upright position shown in Fig. 2 to bring the fiat edge of the lens in contact with the sharp edge of the grinding wheel 2%. The holder 34 is moved inwardly with its carrier 33 and the lens 46 is brought into contact with the stone 2B, the gauge 66 having been moved out of the way.

Successive transverse cuts or grooves are formed -i I in the lens edge and then the lens is ready for the formation of facets. The holder 3a is swung around to contact the stop 38 on the arcuate slide track 28 and the carrier 33 is moved outwardly from the grinding wheel so that the lens 46 will be brought into contact with the wheel 20, the holder 34 being in the slanted or tilted position, shown best in r g. 3. This brings the lens 46 into angular contact with the rounded grinder corner til to produce relatively shallow concave cuts in the lens edge at one side. As described above, successive facets are cut with spacing governed by an appropriate toothed wheel such as the wheels 49, and 51. When facets have been completed around the edge at one side of the lens 46 the releasing lever 48 is pressed to open the lens holder 34 whereupon the lens 45 can be turned over and again clamped in the holder 34 by releasing lever 48, and facets can be formed around'the edge adjacent the other face of the lens 46. Centering of the lens 46 in the holder can be accomplished by any desired means such as by making a removable mark at the center of the lens and positioning it to coincide with a mark in the axial center of the lens holder post 36 and cup or pad 31. The operation of the apparatus is the same for round lenses or lenses which are of non-circular shape, and on the non-circular lenses, as above stated, a toothed spacing wheel of any desired type can be used. A wheel having evenly spaced teeth is probably satisfactory for most purposes, but if desired a wheel having teeth which are irregularly spaced such as the wheel 51 in Fig. 13 can be used to evenly space the facets around the non-circular edge.

In some types of lenses it is desirable to round off the lens edge to some extent and for that purpose I have provided the groove 6| circumferentially of the grinding wheel 28. Of course, this apparatus is so arranged that the lens 46 cannot be held in an edge-to-edge position with respect to the wheel 20, and this type of grinding must be done while the lens 46 is held in the hand. This is merely a finishing operation on lens edges and need not be particularly accurate.

In Figs. 9 and 10 I have illustrated a modified form of lens holder construction. There is a swingable arm 68 comparable to the arm 25 shown in the first construction. This arm has a pivot bolt 69 and wing nut Ill positioned in the same manner as the bolt 26 described above. Extending upwardly from the swinging arm 68 is a post II and pivotally secured to the post at I2 is a unit made up of a pair of ears I3. These are connected to a horizontally disposed bed 14 which is channeled as at I5 and which carries a pinion 16' on a rotary shaft TI. The shaft may be turned by knurled wheels I8. A rack element I9 slidably fits the channel 15 and carries a row of teeth which are in mesh with the pinion It so that said rack I9 can be moved horizontally with-respect to the bed It. The lefthand endof the rack carries a vertical sleeve 8i within which is journalled a shaft 82. The lower end of the shaft. 82 extends from the sleeve 8| and carries a pair of toothed wheels 83 similar to the wheels 49 and 50 in the first embodiment. These wheels 83 may be selectively engaged by a pin 84' similar to the pin 5! shown best in. Figs. 3 and 4. The upper end of the shaft 3-2 has an enlarged end 85 which carries a lens contact cushion or pad as.

Pivotally secured between the upper ends of the ears i3 is a swingable arm 81 which carries on its outer end a rotary lens contact element 83, which has a yielding pad incorporated therewith in the same manner as the element 45 in the first embodiment described. A spring 81a acts on the arm 3! to press the pad 88 toward the pad 85 to clamp a lens between them.

The pivot '52 is provided with a thumb nut 89 which can be loosened to permit the lens holder unit supported by the upright member II to be tilted to an angle simiiar to the angle of the holder shown in Fig. 3. It can, of course, be shifted about its pivot bolt 69 between stops such as the stops 29 and 39 shown in Fig. 1, the arcuate slideway 9%! being the same as the slide 23 in Fig. 1. Furthermore, as stated above, rotation of the pinion I5 will move the rack I9 forwardly or backwardly to similarly move the lens in the lens clamp toward and away from the grinding wheel.

In Figs. 11 and 12 there is shown a swingable arm EiI on a pivot bolt er, the other end of said arm resting upon an arcuate slideway 93 in the same manner as the arm 68 in Figs. 9 and 10. A bracket 94 extends upwardly from the arm 91 and has pivotally mounted at Q5 a rack bed 96 in which is slidable a rack element 97 having teeth 8. These teeth mesh with a pinion 99 as in the embodiment shown in Figs. 9 and 10. On the left-hand end of the rack element 91 is rotatably mounted a cushioned lens engaging element I00 and an upper cushioned lens element IGI is mounted on the end of an arm I02 which is pivoted at I03 to the rack element 91. A spring I04 normally urges the arm I02 downwardly so that the lens contacting pads or cushions I09 and IBI will be relatively tightly clamped together to firmly secure a lens between them. The lower rotatable lens contacting pad or cushion ID!) has a gear 25 secured thereto and this gear meshes with a second gear I06 which is adapted for rotation with a ratchet wheel Iiil. A spring pressed pawl element I08 engages the teeth on the ratchet wheel I01 and is pivotally connected at I09 to a lever III]. This lever III] is pivotally mounted at III to the rack element 91 and is also rigidly connected to a trigger element H2. A spring II3 normally pulls against the lever III] to maintain the trigger IE2 in its left-hand limit of movement, as viewed in Figs. 11 and 12, and when said trigger H2 is pulled to the right by the finger of the operator it will cause the pawl IE8 to move to the left whereby the ratchet wheel I61 and gears 35 and I06 will be rotated with a step-by-step motion. The movement of trigger H2 and actuation of the ratchet wheel l! and gears I and IDS is to be so controlled that the lens cushion I00 and its companion cushion Hll will rotate to similarly move a lens to successive positions for facet grinding.

The rack bed 96 which carries the rack 91 and lens clamping elements I00 and I0! and has a downwardly extending arcuate slotted element H4 which in cooperation with the bolt H5 and wing nut H6 permits tilting of the lens clamping assembly to the desired angle with respect to the grinding wheel such as that shown at 20 in Figs. 1 and 2. It will, of course, be seen that the bolt H5 is mounted in a vertical bracket ill which rises from the swinging arm 9|.

The operation of these devices is basically the same in that they are capable of clamping a lens in generally the same manner. Swinging movement in an arc is positively limited by stops such as the stops 29 and 30, and the device can be tilted to various desired angles with respect to the grinding wheel by reason of the ability to shift the lens clamp toward and away from the wheel. They provide means for positively securing the desired step-by-step movement of the lens to produce accurate spacing of the facets to be formed and consequently the finished grinding job presents a plurality of facets of not only equal spacing but uniform size and depth. In the first two embodiments I provide means for utilizing a pair (or more if desired) of toothed wheels with teeth of different spacing to produce difierently spaced facets and in the embodiment shown in Figs. 11 and 12, while only one ratchet wheel and gear train is shown, it is to be understood that gears of different ratios can be utilized to produce different spacing of facets.

In Fig. 14 there is shown a lens edge portion with corner facets H8 such as are formed by the rounded grinding wheel portion 60 shown in Fig. l. Across the peripheral surface of the lens edge a plurality of V-shaped cuts are formed with the sharp grinding wheel portion 59, thus providing additional facets for further diffusion of light at the lens edge. While I have shown the facets H 8 at the edge corners as being opposite, it is to be understood that those facets on one side can be staggered with respect to those on the other side.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of my invention.

What is claimed is:

1. Apparatus for grinding facets in lens edges comprising a grinding tool, a lens holder positioned adjacent said grinding tool and arranged to hold a lens in grinding relationship to said tool,said holder being manually shiftable to a plurality of successive unevenly spaced positions to shift the lens to a plurality of lens edge positions relative to said grinding tool, and a gauge device for governing the extent of successive shifts of said holder.

2. Apparatus for grinding facets in lens edges comprising a grinding tool, a slide bar mounted for pivotal movement at one end in a plane normal to that of said grinding tool, a slide element on said bar adapted to be moved toward and away from said grinding tool, a lens holder body pivotally secured to and extending upwardly from said slide element, a relatively stationary lens clamping post extending upwardly from said body, and a cooperating lens clamp element movable relative to said post and telescopically slidable in a portion of said body.

3. The method of forming evenly spaced facets in the edges of irregularly shaped lenses which includes, supporting the lens for rotation about a pre-determined center of rotation, rotating the lens with a step-by-step movement, grinding a series of successive facets at spaced intervals, the interval of rotation of the lens about its axis being less where the lens is of greater radial measurement and the interval of rotation being proportionately greater as the radii at different points are shorter.

ALBERT L. ANDERSON. 

